(1) Field of the Invention
The present invention relates to a bellows-shaped corrugated tube as a harness-protecting tube, through which an electric wire passes being bent, for supplying electric power to a slide door, slide seat or the like of a motor vehicle.
(2) Description of the Related Art
FIGS. 6 and 7 shows an example of a harness wiring structure using a conventional corrugated tube (for example, see Japanese Patent Application Laid-Open No. 2001-354085).
The harness wiring structure is for mounting a wiring harness 43 from a slide door 41 of a motor vehicle to a vehicle body 47 so as to supply electric power to electric equipment and auxiliary equipment located on the side of slide door. An outer periphery of the wiring harness 43 is equipped with a corrugated tube 43b made of synthetic resin so as to safely protect a plurality of electric wires 43a from interference with the outside. The corrugated tube 43b includes dented grooves and projecting strips on an outer periphery thereof, which are arranged alternately in a bellows-shape, and has an excellent flexibility. The wiring harness 43 is composed of a plurality of the electric wires 43a and the corrugated tube 43b. 
On the side of the slide door 41, the wiring harness 43 is received in a protector 50 made of synthetic resin with being bent, biased in the upward direction by a leaf spring 44 made of metal, so that a slack of the wiring harness 43 upon half-opening of the slide door 41 is absorbed so as to prevent the wiring harness 43 from hanging down in an intermediate space 46 (see FIG. 7). The leaf spring 44 is fixed on the side of a lower front end of the protector 50 together with the wiring harness 43, wherein a harness fixing part is shown with a reference numeral 59.
The protector 50 is composed of a protector base 51 and a protector cover 52 and fixed to the slide door 41 being placed longitudinally, so that the wiring harness 43 is mounted shakably back and forth in the vehicle from a long lower opening 55 of the protector 50 to a harness-fixing tool 60 situated in the proximity of a step part 48 of the vehicle body 47 through the intermediate space 46.
FIG. 6 shows a fully closed state of the slide door 41, while FIG. 7 shows a half-opened state of the slide door 41, which is close to a fully opened state thereof. On the fully closed state of the slide door 41, the wiring harness 43 is pulled backward, while on the fully opened state of the slide door 41, the wiring harness 43 is pulled forward.
FIGS. 8A and 8B show an example of a conventional corrugated tube 61 (see Japanese Patent Application Laid-Open No. 2007-60754).
The corrugated tube 61 is made of synthetic resin and includes dented grooves (i.e. valley parts) 62 and projecting strips (i.e. mountain parts) 63 on an outer periphery thereof, which are arranged alternately in the longitudinal direction of the corrugated tube 61, and is formed in a bellows-shape. Ribs 64 having a height from an outer peripheral surface 62a of the valley part 62 to an outer peripheral surface 63a of the mountain part 63 are formed integrally with respective end parts situated on the side of long diameter, in a section of the corrugated tube 61 (see FIG. 8B), in the longitudinal direction of the corrugated tube 61, so that stiffness of the corrugated tube 61 in the long diameter direction in the section of the corrugated tube 61 is increased and therefore, the corrugated tube 61 is hardly bent in the long diameter direction thereof.
For example, when the corrugated tube 61 shown in FIG. 8 having a longitudinally long shape in section is used in the harness wiring structure (i.e. electric power supply structure) shown in FIG. 6, the hang of the wiring harness 43 between the slide door 41 and the vehicle body 47 (i.e. in the intermediate space 46) is further restricted.
The corrugated tube 61 shown in FIG. 8 can be applied to a structure, in which a wiring harness on a condition of longitudinally long shape in section for supplying electric power to a slide seat in a motor vehicle is bent in a U-shape so as to be mounted in a laterally long case. Moreover, for use in a slide door, besides the harness wiring structure shown in FIG. 6, the corrugated tube 61 shown in FIG. 8 can be applied to a structure, in which a wiring harness on a condition of laterally long shape in section is bent in a U-shape so as to be mounted in a rectangular case (i.e. protector), a slider is provided slidably in the case, and the wiring harness on a condition of longitudinally long shape in section is mounted from the slider to the side of the vehicle body through the intermediate space. These examples are described in Japanese Patent Application Laid-Open No. 2007-60754.
The corrugated tube 61 shown in FIG. 8 is effective, for example, in a case in which a slide stroke of the slide door is large or in a case in which a biasing means such as a leaf spring is not used to absorb the slack of the wiring harness. However, the corrugated tube 61 shown in FIG. 8 cannot make the slack of the wiring harness completely zero. Therefore, a corrugated tube that can further effectively prevent the slack of the wiring harness from occurring has been required.
Such a requirement can take place in a case in which the corrugated tube is applied to a slide structure such as a slide door of a vehicle except a motor vehicle or a slide door, for example, of a manufacturing apparatus or of an inspecting apparatus other than of a vehicle.